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BRA 
^^NIVERSITT 


BAKING     POWDERS 


A   TREATISE   ON   THEIR    CHARACTER,     METHODS    FOR 

THE   DETERMINATION    OF    THEIR    VALUES,    ETC. 

WITH    SPECIAL    REFERENCE  TO 

RECENT   IMPROVEMENTS    IN   PHOSPHATE   POWDERS. 


BY 

CHARLES  A.  CATLIN,  B.  S.,  Ph.B.,  F.A.A.  A.  S. 


PUBLISHED  BY  THE 

RUMFORD    CHEMICAL   WORKS, 

Providence,  R.  I.,  U.S.A. 

1899. 


Entered  according  to  Act  of  Congress,  in  the  year  1899,  by  the 
Kumford  Chemical  Works,  in  the  office  of  the  Librarian 
of  Congress  at  Washington. 
Rights  of  translation  reserved. 


CONTENTS. 

Baking  Powders.  _  .  .  -  7 

Hygienic  quality. 
Leavening  quality. 
Recent  improvements  in  phosphate  j)Owders. 

Valuation  of  Baking  Powders.  -  -  -  20 

Total  available  carbon  dioxide. 
Conditions  under  which  carbon  dioxide  is  evolved. 
Keeping  quality. 

Carbon  Dioxide  Absorption  Apparatus.     Description.  29 

Improved  Apparatus  for  the  volumetric  determination  of 

Oirbon  Dioxide,  etc.,     Description.  -  -  35 

Kuniford  Chemical  Works.         -  .  .  .  43 


ILLUSTRATIONS. 

A  Corner  of  Rumford  Laboratory              -              -  Frontispiece. 

Photo-Micrographs    of    the    constituents    of    Rumford 

Baking  Powder.                       ...  g 

Absorption  Ai)paratus.               -              -              -  -  28 

Volumetric  Gas  Api)aratus.                     -              -  -  34 

Photo-Micrographic  Camera.                   -              -  -  42 


OF  TTTR 

UNIVBRSITT 
^ALIFOBJ:^ 


Baking  Powders, 


Hygienic  Quality. 

Baking  Powders  have  for  their  essential  constituents, 
sodium  bicarbonate  and  some  form  of  acid  or  acid 
salt.  During  the  bread  making  process  in  which  they 
are  employed,  under  the  influence  of  the  water  or 
other  liquid  used  in  mixing  the  dough,  chemical 
reaction  more  or  less  complete  ensues  between  these 
constituents,  resulting  in  the  evolution  of  the  leaven- 
ing carbon  dioxide  gas,  which  is  eventually  dissipated, 
and  a  fixed  residue,  saline  for  the  most  part,  which 
remains.  It  is,  therefore,  the  character  of  this  residue 
which  determines  the  hygienic  quality  of  any  baking 
powder. 

Based  upon  these  residues,  Baking  Powders  may  be 
conveniently  divided  into  three  well  defined  groups : 

1st.  Baking  Powders  conveying  to  the  food  in  which 
they  are  used,  a  saline  addition  of  phosphates,  for  the 
most  part  of  calcium  and  sodium. 

2nd.  Baking  Powders  conveying  to  the  food  in  which 
they  are  used,  a  saline  addition  of  tartrates,  for  the 
most  part  potassium-sodium  tartrate,  more  commonly 
known  as  the  medicine  Rochelle  salt. 

3rd.  Baking  Powders  conveying  to  the  food  in  which 
they  are  used,  a  saline  addition  of  sodium  sulphate, 
7 


8  Baking  Powders. 

more  commonly  known  as  the  medicine  Glauber's  salt, 
and  an  aluminum  salt,  or  aluminum  hydrate,  or  both, 
as  the  case  may  be. 

Considering  the  hygienic  quaHty  of  powders  of  the 
various  classes,  we  find  in  the  first,  the  residue  left  in 
the  food  is  wholly  composed  of  phosphates,  of  calcium 
and  sodium  for  the  greater  part;  and  that  these  phos- 
phates are  normal  constituents  of  both  animal  and 
vegetable  food.  Furthermore,  we  find  careful  research 
has  demonstrated  animal  life  cannot  exist  without  a 
supply  of  these  phosphates ;  since  they  not  only  go  to 
make  up  an  important  element  of  bodily  structure,  but 
play  an  essential  part  as  well  in  the  process  of  bodily 
nutrition. 

It  has  been  proved  by  research,  in  all  the  higher  forms 
of  animal  Hfe,  if  not  in  every  form  of  animal  life 
without  exception,  there  is  a  demand  for  a  constant 
supply  of  these  phosphates  and  a  corresponding  con- 
stant waste  through  their  utilization  in  the  life  process; 
and  that  the  organs  of  the  animal  body  are  specially 
constructed  for  the  continued  elimination  of  these  phos- 
phate wastes  without  injury,  or  even  the  slightest  dis- 
turbance of  any  of  their  functions. 

These  phosphate  baking  powders  are  in  fact  the  sole 
exemplification  of  leavening  agents  which  do  not  intro- 
duce, as  a  residuum  of  their  action,  material  abnormal 
to  food ;  and  are  further  unique,  in  that  their  residues, 
in  and  of  themselves,  contribute  essential,  salts  in  form 
available  to  the  animal  economy. 

Considering  the  hygienic  quality  of  powders  of  the 
second  class,  wherein  potassium-sodium  tartrate  is  the 
saline    residue,    we   find     this     salt,     while     possessing 


Baking  Powders.  9 

medicinal  and  remedial  value  under  certain  disturbed 
conditions  of  health,  is  never  present  as  a  normal 
constituent  of  the  animal  body,  nor  yet  as  a  normal 
constituent  of  food  of  any  kind ;  neither  does  it  in 
itself  possess  nutritious  value,  nor  contribute  nutrient 
qualities  to  food  in  which  it  may  be  present,  nor 
yet  assist  in  any  degree  the  digestive  function.  The 
use  of  baking  powders,  from  which  it  is  the  resultant, 
is,  in  fact,  defended  by  interested  parties,  only  upon 
claims  for  the  innoxiousness  of  the  residue,  based, 
to  say  the  least,  upon  very  questionable  data.  Hygienic 
quahties  are  never  claimed  for  it,  except  when  it 
shall  have  undergone  a  supposable  change  of  con- 
dition. This  change  of  condition  by  a  most  ingenious 
distortion  of  fact  they  claim  possible,  through  the 
operation  of  certain  obscure  physiological  influences 
decomposing  the  objectionable  tartrate  to  carbonates  ; 
which,  in  some  mysterious  way,  sufficient  phosphate 
being  present  in  the  food,  react  to  become  phos- 
phates ;  when  all  the  virtues,  and  only  the  virtues 
of  phosphates  are  claimed  for  the  resultant.  When 
it  is  considered  that  such  decomposition  of  a  salt, 
if  it  ever  takes  place,  involves  consumption  of  energy 
in  the  operation,  it  certainly  is  questionable  whether 
the  phosphate  derived  by  such  roundabout  process 
has  not  cost  the  animal  economy  more  than  it  will 
ever  receive  in  return ;  especially  when  one  realizes 
that  the  phosphates  of  the  food  were  probably  directly 
available  without  it.  If  it  remains  as  Rochelle  salt  it  is 
certainly  an  open  question  whether  it  be  innoxious. 
Physiologists  have  determined,  while  this  salt  in  doses 


10  Baking  Powders. 

of  one-half  to  one  ounce  is  an  active  cathartic,  in 
smaller  doses  it  is  absorbed  by  the  system  and  renders 
the  urine  alkaline.  A  most  dangerous  condition  if  pro- 
longed, and  one  certainly  not  to  be  invited  by  the  con- 
tinued ingestion  of  the  salt  in  ones  daily  food.  In  fact, 
the  dangers  would  seem  to  be  even  greater  from  the 
small  doses  taken  in  bread  raised  with  powders  of  this 
class  than  from  the  larger  cathartic  doses. 

In  some  cases,  powders  of  this  class,  being  prepared 
by  the  employment  of  a  portion  of  free  tartaric  acid, 
leave  as  an  element  of  their  saline  residue,  sodium  tar- 
trate, a  salt  quite  as  objectionable  as  the  Rochelle  salt, 
with  no  hygienic  qualities  whatever  to  recommend  it. 

Summing  up  then  the  qualities  of  this  second  class 
of  powders,  we  cannot  but  be  led  to  the  conclusion,  that 
their  employment  in  food  is,  to  say  the  least,  decidedly 
unhygienic. 

The  hygienic  quality  of  powders  of  the  third  class, 
commonly  called  ''Alum"  powders  (or  "Alum-Phos- 
phate" when  a  little  phosphate  is  added)  wherein  the 
residue  of  their  operation  consists  of  sodium  sulphate 
and  aluminum  hydrate,  or  an  aluminum  salt  like  the 
basic  sulphate  or  the  phosphate,  is  certainly  question- 
able. Sodium  sulphate,  commonly  known  as  Glauber's 
salt,  like  Rochelle  salt,  is  an  active  cathartic  in  doses 
of  one-half  to  one  ounce,  but  of  much  less  injurious 
possibihties  when  taken  in  smaller  doses  long  con- 
tinued, being  really  a  normal  excretion  of  the  body. 
But  its  nauseous  taste  gives  it  a  most  objectionable 
quality  in  bread  making.  It  may  therefore  be  called  a 
harmless  though  undesirable  resultant.       Not  so  of  the 


Baking  Powders.  11 

aluminum  constituent  of  the  residue  from  this  class  of 
powders,  the  presence  of  which  is,  without  doubt, 
exceedingly  dangerous  in  food,  especially  in  that  of 
invalids  or  of  persons  having  weak  digestive  powers. 
It  is  claimed  by  interested  parties,  that  when  a  phos- 
phate is  used  in  connection  with  the  aluminum  salt  in 
the  composition  of  these  powders,  the  residue  of  the 
operation  in  food  is  an  insoluble,  and  consequently 
harmless,  aluminum  phosphate.  Facts  however  do 
not  seem  to  prove  that  aluminum  phosphate  is  insol- 
uble in  the  juices  of  the  stomach.  And  furthermore, 
extended  investigation  shows  that  when  phosphate 
addition  has  been  made  to  baking  powders  having  an 
aluminum  salt  for  their  active  acid  ingredient,  it  is  never 
in  anywhere  near  the  required  proportion  to  combine 
with  all  the  aluminum  present.  The  real  purpose  of  its 
addition  being  to  give  a  quick  acting  property  to  the 
powder,  which  it  lacks  when  the  aluminum  salt  alone 
is  employed  as  the  acid  agent,  and  not  to  supply  the 
phosphate  for  the  reaction  to  aluminum  phosphate, 
nor  yet  because  of  its  hygienic  quality.  It  is  fur- 
ther true,  that  in  baking  powders  where  alum  or 
aluminum  sulphate  is  the  active  acid  agent,  especially 
if  it  be  in  the  dried  anhydrous  condition,  the  reactions 
of  the  baking  process  are  Hable  to  be  incomplete,  and 
basic  aluminum  sulphate  result,  which  cannot  be  other 
than  a  dangerous  addition  to  food.  Chemical  and 
physiological  literature  teems  with  testimony  to  the 
exceedingly  baneful  results  following  the  administration 
of  soluble  aluminum  salts  of  any  kind.  In  regard  to 
aluminum  hydrate  there  is  a  large  amount  of  testimony 


12  Baking  Powders. 

from  high  authorities,  all  to  the  effect  that  it  acts  to 
retard  digestion,  if  not  wholly  to  arrest  it;  that  it  enters 
into  insoluble  combination  with  valuable  constituents  of 
food  to  render  them  unavailable,  especially  the  albumin- 
oids and"  phosphates ;  beside  having  an  irritant  and 
highly  astringent  effect  upon  the  mucous  membrane  of 
the  alimentary  canal ;  while  some  assert,  that  it  pro- 
duces a  most  disastrous  effect  upon  the  nervous  system. 

Leavening  Quality. 

Of  course  the  hygienic  quality  of  a  baking  powder 
is  of  first  importance,  but  for  its  designed  purpose 
there  are  other  qualities  which  determine  its  value. 

It  is  perfectly  understood,  that  the  object  of 
any  leavening  process  is  to  impart  a  light  cellular 
structure  to  the  finished  loaf  or  cake ;  and  that  this  is 
effected  generally  by  in  some  way  evolving  carbon 
dioxide  within  the  dough,  in  proper  quantity,  and  at 
the  proper  stage  of  the  cooking  or  baking  operation. 
Baking  powders  are  means  to  this  end ;  and  for  their 
true  valuation  a  clear  understanding  of  the  cooking  or 
baking  process  is  necessary. 

In  an  article  published  in  the  Journal  of  Analytical 
Chemistry,  Vol.  IV,  Page  361,  October,  1890,  I  gave 
details  of  some  investigations  of  mine  upon  the  con- 
ditions of  the  baking  process,  which  will  be  useful  to 
us  in  this  connection.     From  this  I  quote : 

**To  inform  myself  more  exactly,  I  made  many  care- 
ful observations  of  the  steps  pursued  by  a  cook  of  the 
best  homespun  order,  in  preparation  of  baking  powder 
biscuit  dough  and  subsequent  baking  of  the  same.     I 


Baking  Powders. 


13 


found  that  she  was  using  about  504  gms.  of  flour 
(Haxall  brand)  for  the  quart,  as  leavening  for  which 
two  heaping  teaspoonfuls  of  a  popular  brand  of  baking 
powder,  weighing  together  about  17  gms.,  and  for 
moistening,  386  gms.  of  either  milk  or  water,  or  about 
23  CO.  of  liquid  for  each  gram  of  baking  powder 
employed. 

The  range  of  temperature  and  the  length  of  exposure 
thereto,  were  noted  as  follows :  When  the  dough  was 
ready  for  baking,  a  thermometer  was  inserted  so  that 
the  bulb  might  be  held  as  near  as  possible  at  the  centre 
of  the  biscuit  or  loaf,  and  the  whole  placed  in  the 
already  heated  oven  by  the  cook  in  the  usual  manner, 
the  range  of  temperature  being  observed  through  a 
peephole,  and  record  made  thereof  at  stated  times. 

Averaging  a  series  of  accordant  results  thus  obtained, 
I  found  the  oven  at  the  outset  to  have  a  temperature 
of  about  380°  F.,  and  that  the  temperature  of  the 
interior  of  the  dough  passed  through  the  following 
range : 

•    After    1  minute's  exposure  in  the  oven 
''       3 

**  5 
7 

**  10 

''  12 

''  13 

**  15 

'^  17 

After  thirteen  minutes  exposure,  the  cook  pronounced 
the  biscuit  **done"  ;    but  for  the  sake  of  the  experiment, 


le  oven 

95°  F.. 

130°  '' 

150°  '' 

160°  '' 

205°  '* 

205°  '' 

210°  - 

212°  - 

212°  '' 

217°  - 

14  Baking  Powders. 

the  heating  was  continued,  when,  after  fifteen  minutes, 
the  crust  had  become  far  too  brown  to  be  palatable, 
while  at  the  end  of  seventeen,  actual  burning  had  well 
commenced.  From  the  above  it  is  apparent  then, 
that  in  the  actual  baking  process,  the  temperature  of 
the  dough  is  raised  gradually,  through  a  lapse  of  about 
thirteen  minutes,  to  a  temperature  of  not  more  than 
212°  F.,  and  for  a  successful  issue  this  should  not 
endure  for  more  than  one  minute,  if  indeed  it  should 
be  allowed  to  continue  for  that  length  of  time." 

In  the  first  place,  all  ordinary  operations  of  the 
kitchen,  if  graduated  at  all,  are  by  measure  and  not  by 
weight.  The  quart  of  flour  demands  the  two  or  three 
teaspoonfuls  of  baking  powder,  always  measured,  never 
weighed.  It  has  been  found  that  somewhere  about  68 
cubic  inches  of  carbon  dioxide  gas  is  the  proper  volume 
to  raise  1  quart  of  flour,  loosely  packed  (1  lb.)  ;  or  a 
little  less  than  a  volume  and  a  quarter  of  gas  to  one 
volume  of  the  flour  for  ordinary  biscuit  or  bread.  Very 
much  less  than  this  gives  poor  results  ;  while  very  much 
more  is  practically  of  no  value.  Stating  this  another 
way:  Experience  has  taught  that  in  domestic  use  a 
powder  properly  evolving  50  times  its  own  volume  of 
gas  is  about  the  right  standard.  The  available  gas- 
evolving  power  of  a  baking  powder  to  meet  the  com- 
mon domestic  requirements  should  then  be  somewhere 
about  50  to  60  times  that  of  its  own  volume.  That  is  to 
say,  a  baking  powder  should  have  a  volumetric  leavening 
^^  or  aerating  coefficient  of  50  to  60.  This  is  indeed  a 
very  important  question  in  determining  the  value  of  a 
baking  powder,  which  is  not  a  question  of  percentage  by 


Baking  Powders.  15 

weight,  but  one  wholly  of  percentage  by  volume.  For 
it  is  readily  seen,  that  as  much  leavening  value  may  be 
obtained  in  domestic  use  from  the  same  volume  of 
powder  purchased,  in  one  having  a  low  percentage  of 
carbon  dioxide  with  high  density,  as  from  one  having 
high  percentage  of  carbon  dioxide  with  low  density. 
Therefore,  the  true  measure  of  efficiency  of  a  baking 
powder  is  one  dependent  upon  volumetric  considera- 
tions, and  not  one  of  percentage  by  weight,  as  is  usually 
reported. 

But  this  available  carbon  dioxide  does  not  tell  the 
whole  story  of  baking  powder  valuation  by  any  means. 
It  is  almost  as  important  to  know  the  manner  of  its 
evolution  as  it  is  to  know  its  total  volume.  When  one 
considers  the  dough  mixing  process  it  is  easily  under- 
stood, if  a  baking  powder  be  employed  which  gives 
a  too  prompt  reaction,  much  of  the  leavening  gas  will 
be  evolved  and  lost  in  the  manipulation,  especially  if 
the  dough  be  rolled  and  handled.  In  thin  batter,  like 
griddle  cake  batter,  especially  where  considerable  time 
necessarily  elapses  between  the  mixing  and  the  cook- 
ing, this  quick  cold  evolution  is  a  matter  of  serious 
importance. 

It  is  manifest  also,  on  the  other  hand,  that  a  baking 
powder  too  tardy  in  character,  requiring  a  high  oven 
temperature  to  bring  about  reaction,  cannot  give  good 
results.  When  such  baking  powder  is  used,  the  dough 
placed  in  the  hot  oven  is  speedily  crusted  over,  long 
before  the  interior  of  the  loaf  has  attained  the  reacting 
temperature,  and  the  mass  of  the  dough  itself  under  the 
oven    influence    has  become  considerably  solidified  as 


16  Baking  Powders. 

well.  When  now  the  exciting  temperature  is  attained, 
the  reaction  ensues  with  almost  explosive  violence, 
producing  a  result  that  is  anything  but  the  delicate 
cellular  structure  desired.  The  conditions  under  which 
the  evolution  of  the  gas  takes  place  is,  therefore,  a 
most  important  consideration  in  the  valuation  of  a 
baking  powder. 

It  is  plain  that  a  baking  powder  evolving  its  carbon 
dioxide  quite  gradually  from  the  first  of  the  mixing  pro- 
cess and  on  into  the  oven,  not  so  tardy  as  to  require  the 
extreme  heat  of  the  baking  process,  nor  yet  so  active 
as  to  expend  itself  entirely  by  the  cold  evolution,  is  the 
ideal.  To  measure  this  quality  of  a  baking  powder,  is 
really  a  very  difficult  matter.  A  useful  determination 
indicating  something  in  this  direction  is  that  of  the 
amount  of  carbon  dioxide  given  off  simply  in  the  cold, 
when  treated  with  the  quantity  of  water  used  in  mixing 
the  dough. 

The  question  of  the  amount  of  water  to  be  used  to 
fairly  represent  the  conditions  of  the  baking  process  is 
one  of  some  moment.  Referring  again  to  my  investiga- 
tion of  the  conditions  of  the  baking  process :  In  actual 
process  we  found  that  23  cc.  of  water  were  employed 
for  each  gram  of  baking  powder.  A  large  part  of  this 
water,  being  absorbed  by  the  flour,  must  have  been 
practically  inert  in  bringing  about  reaction  between  the 
constituents  of  the  powder.  Just  what  this  absorbed 
water  would  be,  we  have  not  the  means  of  determining; 
but  certainly,  not  more  than  half  the  water  employed 
can  be  considered  as  exerting  solvent  action  upon  the 
powder.       I  would  therefore  recommend  that  not  more 


Baking  Powders.  17 

than  10  cc.  be  used  for  each  gram  of  baking  powder 
taken  in  making  the  determination.  This  amount  of 
water,  of  course,  also  represents  that  necessary  to  imi- 
tate the  whole  baking  process,  oven  operations  and  all. 

In  the  oven  baking,  however,  the  further  elements 
of  temperature  and  time  come  in  for  consideration. 
Referring  again,  on  this  point,  to  my  investigation : 
We  found  in  our  observations  of  the  baking  of  the  biscuit, 
that  in  the  matter  of  temperature,  212^  F.  was  never 
exceeded  within  the  dough  in  proper  manipulation,  and 
that  this  limit  should  never  be  allowed  to  endure  for 
more  than  one  minute  at  the  longest.  As  a  matter  of 
fact,  I  believe  that  when  the  temperature  reaches 
200^  F.,  or  even  at  a  much  lower  point,  the  dough  has 
attained  such  consistency  that  further  evolution  of  gas 
is  rather  an  injury  than  an  advantage.  However  this 
may  be,  it  is  certain  that  gas  evolved  beyond  the  limit 
of  a  temperature  of  212°  F.,  enduring  for  one  minute, 
is  of  no  practical  value. 

Upon  the  operation  of  the  baking  process  as 
observed,  fixing  the  conditions  of  moisture,  time  of 
cold  evolution,  time  of  heating,  etc.,  I  have  based  the 
methods  for  the  valuation  of  baking  powders  described 
in  the  context. 

As  I  have  said,  this  matter  of  extra-oven,  or  cold- 
evolution,  of  the  carbon  dioxide  of  a  baking  powder,  is 
one  of  great  importance ;  and  one  to  which  the  manu- 
facturer should  be  keenly  alert.  To  adjust  this  ratio 
between  the  total  available  and  the  cold  carbon  dioxide 
to  greatest  efficiency  for  all  kinds  of  baking  work, 
would  be  out  of  the  question ;  for  this  would  demand 


18  Baking  Powders. 

for  cake  one  ratio,  for  biscuit  another,  for  griddle  cakes 
another,  etc.  Thus  this  adjustment  becomes  a  matter 
of  judgment  as  to  average  efficiency  in  the  baking 
operations  of  the  household. 

A  ratio  somewhere  between  60  and  70  for  this  cold,  to 
the  100  available  carbon  dioxide,  seems  to  best  meet 
the  popular  favor,  and  is  about  the  ratio  adopted  for 
the  better  class  of  powders. 

Recent  Improvements  in  Phosphate  Powders. 

The  pecuhar  value  of  acid  calcium  phosphates  in 
healthfulness  and  efficiency,  was  early  appreciated  by 
Professor  Horsford,  who  first  suggested  their  use  and 
invented  processes  for  their  manufacture  in  suitable  form 
for  culinary  purposes.  But  there  was  one  quality  of 
these  acidulated  phosphates,  as  he  was  then  only  able  to 
prepare  them,  which  for  many  years  seemed  to  forbid 
their  successful  employment  as  active  acid  components 
of  baking  powders  to  be  packed  in  unsealed  cans.  This 
was  in  their  powerful  avidity  for  moisture,  or  deliques- 
cent property ;  which,  it  is  readily  understood,  would 
be  fatal,  in  unsealed  packages,  to  any  reasonable  com- 
mercial stability.  But  years  of  patient  research  was  at 
length  rewarded  by  the  discovery  of  a  process  through 
which,  to  the  surprise  of  everyone  who  had  been 
familiar  with  past  efforts,  a  baking  powder  composed 
only  of  monocalcium  phosphate,  sodium  bicarbonate 
and  starch,  might  be  prepared,  which  was  even  supe- 
rior to  potassium  bitartrate  baking  powders  in  the 
quality  of  commercial  stability.  The  valuable  qualities 
of  the  new   discovery   were  soon  turned    to    practical 


Baking  Powders.  19 

account  in  preparing  the  powder  now  sold  under  the 
name  of  Rumford  Baking  Powder,  made  by  the  Rum- 
ford  Chemical  Works,  of  Providence,  R.  I.,  the  original 
manufacturers  under  Professor  Horsford's  patents  and 
with  whom  he  was  identified.  This  baking  powder  is 
composed  of  pure  monobasic  orthophosphates,  mostly 
of  calcium  with  the  usual  small  traces  of  magnesium, 
sodium  and  iron,  pure  sodium  bicarbonate  and 
pure  corn  starch.  These,  by  pecuhar  processes  of 
manipulation,  are  so  brought  together  into  admixture 
as  to  form  a  baking  powder  having  commercial  stability 
equal  to  and  even  excelling  anything  heretofore  pro- 
duced. A  most  wonderful  transformation  has  thus 
been  effected ;  the  phosphate  baking  powder,  once  the 
most  unstable,  now  being  the  most  stable  powder  on  the 
market.  This  result  presents  but  another  illustration 
of  what  patient,  determined  research  may  accomplish 
in  overcoming  apparently  insurmountable  obstacles. 


Valuation  of  Baking   Powders. 


From  our  observations  of  the  practical  operation  of 
Baking  Powders,  three  questions  present  themselves  for 
consideration  in  their  quantitative  valuation. 

First, — The  total  carbon  dioxide  available  in  the 
baking  process. 

Second, — The  conditions  under  which  evolution  of 
the  carbon  dioxide  takes  place. 

Third, — The  keeping  quahty,  i.  e.,  the  power  of 
resistance  to  deteriorating  atmospheric  influence. 

The  first  two  may  be  referred  to  an  arbitrary 
standard ;  while  the  third  must  be,  from  the  very  nature 
of  the  case,  purely  relative. 

Total  available  Carbon  Dioxide. 

Weigh  out  5  grams  of  sample  into  the  evolving 
bottle  A  of  my  volumetric  carbon  dioxide  apparatus, 
for  description  of  which  see  context,  and  determine  the 
total  carbon  dioxide  by  evolution  with  acid  as  therein 
described.  Or  the  total  carbon  dioxide  may  be  deter- 
mined by  any  other  reliable  method.  For  this  work, 
however,  my  apparatus  possesses  special  advantages  in 
rapidity  and  accuracy. 

Weigh  into  a  200  cc.  flask,  or  one  of  any  convenient 
capacity,  2  grammes  of  sample,  add  thereto  20  cc.  of 
20 


Valuation  of  Baking  Powders.  21 

water,  and  heat  to  rapid  boiling  for  one  minute ;  while 
yet  hot,  aspirate  the  flask,  until  all  gaseous  carbon 
dioxide  is  removed ;  then  attach  to  a  soda-lime  tube, 
or  other  form  of  absorption  apparatus,  (for  convenient 
arrangement  of  absorption  apparatus  see  context,)  and 
liberating  it  from  the  residue  in  the  flask  by  use  of 
acid,  observing  all  the  well  known  precautions  necessary, 
determine  the  carbon  dioxide  therein.  This  gives 
the  excess  of  carbon  dioxide  remaining  in  the  sample 
after  reaction  per  se.  Deducting  this  excess  carbon 
dioxide  from  the  total  carbon  dioxide  obtained,  gives 
available  carbon  dioxide  in  the  sample. 

For  consideration  of  the  amount  of  water  to  be 
employed,  and  the  application  of  heat  to  imitate  the 
baking  process,  see  article  upon  '^Commercial  Valuation 
of  Cream  of  Tartar  Substitutes"  by  Charles  A.  Catlin, 
Journal  of  Analytical  Chemistry,  Vol.  IV,  page  361, 
1890,  the  essential  features  of  which  we  have  already 
discussed.      (See  page  12.) 

It  is  preferable  to  determine  total  carbon  dioxide 
and  excess  carbon  dioxide,  and  by  difference  obtain 
available  carbon  dioxide ;  than  to  determine  available 
carbon  dioxide  directly ;  because  of  the  difficulties  of 
evolution  and  absorption  encountered  in  the  latter 
method. 

These  give  percentage  by  weight.  Since,  however, 
baking  powders  are  never  used  by  weight,  but  always 
by  measure  (volume),  an  important  factor  is  to  obtain 
the  gravimetric-density  of  the  sample;  that  is,  its  com- 
mercial volume ;  and  from  this  to  calculate  its  total 
volumetric  leavening  or  aerating  coefficient.     Of  course. 


22  Valuation  of  Baking  Powders. 

one  may  obtain  the  density  of  the  powder  by  any  of 
the  well  known  methods ;  but  the  exact  commercial 
condition  in  which  it  reaches  the  consumer,  is  more 
nearly  arrived  at  by  measurement  of  the  contents  in  the 
package  when  opened.  For  instance,  the  space 
occupied  by  the  powder  in  a  can  as  received,  is  easily 
determined  ;  this  taken  with  the  total  weight  of  contents 
gives  data  for  arriving  at  commercial  density. 

Thus  we  get  weight  of  a  cubic  inch  of  powder  in 
commercial  condition,  and,  from  analysis  obtained, 
calculate  to  cubic  inches  its  carbon  dioxide  at  0^  C. 
and  normal  pressure  (760  mm).  -  Suppose  we  get  in 
this  way  50  cubic  inches  of  gas ;  we  would  then  have  a 
volumetric  leavening  (aerating)  coefficient  of  50.  This 
then  means,  that  a  given  volume  of  the  sample  of 
baking  powder  will  yield  in  the  baking  process,  50 
times  its  volume  of  leavening  gas.  This  is  a  very  im- 
portant question  to  be  considered  ;  as  it  is  readily  seen, 
that  as  much  actual  leavening  value  may  be  obtained 
in  domestic  use  from  a  powder  having  low  percentage 
of  carbon  dioxide  with  high  density,  as  from  one 
having  high  percentage  carbon  dioxide  with  low 
density.  Therefore,  the  true  measure  of  efficiency 
is  not  one  of  weight  percentage  carbon  dioxide,  as  is 
usually  reported,  but  one  of  volume  evolution. 

Conditions  under  which  Carbon  Dioxide  is  Evolved. 

Weigh  5  grammes  of  the  sample  into  the  evolving 
bottle  A,  of  my  volumetric  carbon  dioxide  apparatus, 
using  50  cc.  of  water  in  place  of  the  acid  as  described, 
and  determine  at  normal  temperature  the  carbon  dioxide 


Valuation  of  Baking  Powders.  23 

evolved  after  twenty  minutes  of  reaction.  This  gives 
the  so-called  cold  strength  of  the  sample,  serving  as  an 
approximate  measure  of  the  aerating  power  outside  the 
oven.  Burnt  alum  powders,  for  instance,  under  these 
conditions,  give  but  little ;  while  those  made  from  free 
tartaric  acid  evolve  nearly  all  their  available  gas. 

The  ratio  between  the  total  available,  and  the  cold 
available  carbon  dioxide,  is  a  matter  of  careful  adjust- 
ment in  skilled  manufacture ;  and  effort  is  made  to  bring 
it  to  the  point  of  greatest  efficiency.  It  is  readily  under- 
stood that  a  powder  evolving  all  its  available  gas  in  the 
cold,  presents  great  opportunity  for  excessive  loss  of 
leavening  power  during  the  mixing  of  the  dough,  with 
disastrous  results  in  the  finished  product;  while  one  so 
tardy  in  its  action  as  to  require  the  heat  of  the  oven  to 
excite  it,  can  produce  nothing  but  disappointing  results, 
the  leavening  gas  escaping  from  the  cracks  of  the  crusted 
dough  without  producing  the  desired  cellular  condition. 

Keeping  Quality. 

Atmospheric    moisture    is    the    deteriorating    agent 
assailing  baking  powders.  From  the  very  nature  of 

their  composition,  all  are  susceptible  to  its  influence  in 
a  greater  or  less  degree.  The  measure  of  resistance  to 
this  influence,  of  any  sample,  must  therefore  be  purely 
relative.  It  is  obtained  by  exposing  a  series  of  samples 
under  consideration,  to  the  influence  of  an  artificially 
moistened  atmosphere  produced  in  a  bell  glass  over 
water.  Exposure  to  such  an  atmosphere,  of  course,  is 
an  extreme  test,  since  it  is  saturated  with  moisture ; 
a  condition  rarely  if  ever  encountered  in  commercial 
exposure. 


24  Valuation  of  Baking  Powders. 

First,  in  each  of  the  thoroughly  mixed  samples,  the 
total  carbon  dioxide  content  is  determined,  preferably 
in  my  volumetric  carbon  dioxide  apparatus ;  then  a 
series  of  5  gram  charges  are  weighed  up  from  each 
sample  and  placed  upon  watch  glasses.  A  wire  net 
being  fixed  over  the  water  under  the  bell  glass,  but  not 
touching  it,  these  watch  glasses  with  their  contents  are 
placed  upon  it  (all  under  the  same  bell  glass),  and  kept 
there  for  the  length  of  time  the  exposure  is  desired. 
At  the  end  of  the  exposure  they  are  removed,  and  the 
total  carbon  dioxide  content  determined  in  each,  in  my 
volumetric  apparatus,  or  by  other  means.  The  differ- 
ence between  the  total  carbon  dioxide  at  start  and  the 
total  carbon  dioxide  in  the  charge  after  exposure, 
represents  the  relative  loss  for  each  sample  under  the 
same  condition.  This  loss  calculated  into  per  cent, 
upon  the  total  carbon  dioxide  at  the  start,  of  course 
gives  fair  measure  for  comparison.  To  illustrate : 
Suppose  we  have  three  samples  of  baking  powder  we 
wish  to  compare  as  to  keeping  quality,  A,  B  and  C, 
through  periods  of  ten,  twenty  and  thirty  hours  of  the 
moist  air  exposure.  We  first  determine  the  total  carbon 
dioxide  percentage  in  each ;  then  weigh  out  on  watch 
glasses  three  charges  of  5  grammes  each  from  sample 
A,  marking  them  A^,  A^  and  A^ ;  from  sample  B  three 
charges  of  like  weight  each,  marking  them  B^,  B^  and 
B^;  and  the  same  from  sample  C,  marking  them  C^,  C^ 
and  C^..  All  of  these  nine  samples  are  placed  at  the 
same  time  in  the  same  saturated  atmosphere  under  the 
bell  glass,  and  the  time  noted.  After  ten  hours,  charges 
A-^,  B^  and  C^  are  removed  and  their  carbon  dioxide  con- 


Valuation  of  Baking  Powders.  25 

tents  determined.  After  twenty  hours  total  exposure, 
charges  A^,  B^  and  C^  are  removed  and  their  carbon 
dioxide  contents  determined.  And  after  thirty  hours 
total  exposure,  charges  A^,  B^  and  C^  are  likewise 
removed  and  carbon  dioxide  contents  determined. 
Any  convenient  number  of  samples  may  be  carried 
through  in  series,  and  any  desired  length  of  exposure 
adopted.  Finally  the  carbon  dioxide  loss  calculated 
into  per  cent,  of  carbon  dioxide  at  start,  gives  the 
basis  for  comparison.  In  this  manner  the  relative 
keeping  quality  may  be  determined  between  samples  of 
baking  powders ;  and  experience  has  shown  that  the 
results  obtained  accord  with  atmospheric  exposures. 


Fig.  1. 


Front  view. 


r 
\ 

! 
1 

1 

m 

m 

''^ma 

V 

M 

h 

^M 

if^ 

a 

r 

■ — \ 

^^ 

■%3 

,;  :.,.,::,,,:■;;;.;,,  ..H'     ■   ;■■ 

'      .      '          .-'-   ..'■    ,^...u-       . 

l^flJjJIjII^^^Pf:- 

i^v^.  2. 


Back  view. 


Absorption  Apparatus,  used  in  the  Rumford  Laboratory  for  the 
gravimetric  determination  of  carbon  dioxide. 


Carbon  Dioxide  Absorption   Apparatus. 


A  convenient  and  compact  arrangement  for  a  carbon 
dioxide  absorption  apparatus  which  I  have  devised,  may 
be  described  as  follows,  reference  being  had  to  the 
accompanying  cuts.  Fig.  1  showing  a  front  view,  Fig.  2 
a  back  view : 

Upon  the  base  M  is  fixed  the  longitudinal  upright  N, 
and  about  midway  of  this,  the  transverse  upright  P^ 
these  to  support  and  hold  in  position  the  U-tubes,  etc, 
forming  the  essential  parts.  A  is  the  generating  flask 
of  convenient  capacity,  K  a  reservoir  for  the  decom- 
posing acid  with  tube  running  to  the  bottom  of  A,  con- 
necting through  h  with  the  catch  bottle  H  containing 
soda-lime,  to  retain  any  atmospheric  carbon  dioxide 
when  air  is  aspirated  through  it.  B  is  a  small  bulb 
U-tube  fixed  upon  the  front  side  of  the  longitudinal 
upright  at  its  left  hand  end,  containing  concentrated 
sulphuric  acid,  connecting  at  one  hmb  with  the  exit  tube 
a  of  the  flask  A  and  at  the  other  limb  with  the  tube  b. 
C  is  a  plain  U-tube  fixed  upon  the  back  of  the  upright 
N,  as  shown  in  Fig.  2,  connecting  with  B  by  tube  by  con- 
taining pumice  stone  saturated  with  concentrated  sul- 
phuric acid.  D  is  a  plain  U-tube  fixed  upon  the  trans- 
verse upright  P,  connecting  with  C  by  c,  containing 
pumice  stone  treated  with  cupric  sulphate,  as  a  catch 
29 


30  Absorption  Apparatus. 

tube  for  hydrochloric  acid.  E  is  the  soda-lime  absorp- 
tion U-tube  connected  with  T>  by  d.  F  is  the  drying 
tube  containing  pumice  stone  saturated  with  concen- 
trated sulphuric  acid,  connected  directly  with  E.  E  and 
F  together,  with  the  tube  d  forming  the  parts  to  be 
weighed.  G  is  a  plain  U-tube  fixed  upon  the  back  of 
the  upright  N,  as  shown  in  Fig.  2,  connecting  with  F 
by  the  tube  e,  containing  pumice  stone  saturated  with 
concentrated  sulphuric  acid,  serving  as  a  catch  tube  for 
any  atmospheric  moisture  which  otherwise  might  retreat 
into  the  tubes  E  and  F.  £"  connects  G  with  an  aspi- 
rator, /is  a  wire  loop  suspending  the  couplet  E  and 
F  upon  the  hook  as  shown. 

The  method  of  operating  this  apparatus  is  as  follows  : 
The  absorption  couplet  E  F  being  detached  by 
drawing  off  the  tube  d  from  D,  and  e  from  F,  and 
connecting  d  with  F,  is  thus  completely  sealed  from 
absorption  from  the  air.  In  this  condition  the  weight 
of  E  F  d  is  carefully  obtained  by  suspending  from  the 
pan  hook  of  the  balance  by  the  wire  loop  /.  When 
the  weight  is  obtained,  the  couplet  is  re-attached  to  the 
apparatus  in  its  former  position.  The  weighed  charge 
of  the  material  in  which  the  carbon  dioxide  is  to  be 
determined,  having  been  introduced  into  the  flask  A  and 
the  requisite  amount  of  decomposing  acid  into  K  with 
the  stopcock  closed,  the  whole  apparatus  is  connected 
as  shown  in  the  cut.  The  aspirator  being  set  in  opera- 
tion, the  stopcock  of  K  is  opened  and  the  acid  allowed 
to  flow  down  into  A,  the  aspirating  air  current  flowing 
along  first  through  soda-lime  bottle  H,  to  remove  all 
atmospheric  carbon  dioxide,  thence  through  /ly  K,  A, 


Absorption  Apparatus.  31 

a^  B,  by  C,  c,  D,  d,  E,  F,  e,  G,  g.  The  stopcock  of  K 
being  now  closed,  heat  is  apphed  to  the  flask  A  and 
its  contents  brought  to  a  rapid  boil  continued  for  a  few 
minutes.  The  tube  h  now  being  disconnected  from  H 
is  dipped  into  a  quantity  of  boiling  water  and  the  stop- 
cock of  K  opened  again,  when  the  flask  A  is  allowed 
to  completely  fill  with  the  hot  water,  up  and  into  the 
elbow  of  the  glass  tube,  where  the  rubber  tube  It  is 
attached.  In  this  manner  the  atmosphere  of  A  is  at 
once  displaced  and  much  time  saved  in  unnecessary 
aspiration.  The  rubber  tube  a,  being  pinched  mean- 
while, is  drawn  off  from  A  and  affixed  to  H,  which 
thus  cuts  out  A  and  its  attachments,  and  leaves  the 
course  of  the  aspirating  current  to  flow  through  H, 
^,  B,  by  C,  c,  D,  dy  E,  F,  e,  G,  gy  the  carbon  dioxide 
being  quickly  swept  through  the  series  and  absorbed 
by  the  soda-lime  of  E.  The  current  of  pure  air  may 
be  drawn  through  the  apparatus  at  this  stage  with  con- 
siderable rapidity ;  at  the  rate  of  four  or  five  litres  at 
least,  within  ten  minutes,  without  fear  of  error ;  which 
would  not  be  the  case  had  the  flask  A  with  its  steaming 
contents  remained  in  the  circuit,  when  certainly,  in  such 
rapid  flow,  some  moisture  would  have  been  carried 
beyond  B,  C  and  D  into  the  absorption  couplet.  The 
concentrated  sulphuric  acid  in  B  should  be  changed 
with  almost  every  determination,  thus  maintaining  C 
for  a  long  time  in  efficient  condition.  The  effect 
of  boiling  A  is  of  course  to  heat  up  the  contents 
of  B,  which  is  desirable;  for,  while  concentrated 
sulphuric  acid  has  but  slight  cold  absorption  for  carbon 
dioxide,   it  nevertheless  would   absorb   a  trace,  giving 


32  Absorption  Apparatus. 

error  to  that  extent,  which  might  be  appreciable  should 
excessive  sulphuric  acid  be  used.  Allowing  the  sul- 
phuric acid  in  B  to  heat  up  slightly,  prevents  absorp- 
tion of  any  carbon  dioxide  therein,  yet  forming  an 
efficient  trap  for  moisture.  Of  course  the  sulphuric 
acid  used  in  the  other  drying  tubes  of  the  apparatus 
would  have  this  property  of  slight  absorption  of  car- 
bon dioxide  and  introduce  a  source  of  error,  were  it 
not,  that,  by  allowing  a  current  of  dry  carbon  dioxide 
to  flow  through  these  drying  tubes  for  a  few  moments, 
previous  to  using  for  the  first  time,  (of  course  not 
through  the  absorption  tube,)  and  then  aspirating 
with  pure  air  before  actual  use,  the  sulphuric  acid  is 
saturated  and  error  from  this  source  avoided.  This 
apparatus  furnishes  a  rapid  and  accurate  means  for 
determining  carbon  dioxide  by  absorption. 


XTb  r  a 


OF  THE  ^ 

UNIVERSITY 


Improved    apparatus   for   the    volumetric 
determination   of  Carbon   Dioxide 
and   other   gases.  ^ 


For  the  determination  of  small  quantities  of  carbon 
dioxide  in  readily  decomposed  carbonates,  the  process 
and  apparatus  devised  by  Dr.  Scheibler  presents  a  most 
convenient  and  rapid  method ;  but  the  inability  to  thus 
measure  large  quantities  of  gas  has  restricted  its  em- 
ployment for  the  most  part  to  determination  of  carbon- 
ate in  bone-char.  To  extend  the  field  of  volumetric 
carbon  dioxide  determination  I  have  devised  the  follow- 
ing described  apparatus,  retaining,  as  far  as  possible, 
the  essential  features  of  the  Scheibler. 

Referring  to  the  cut :  A,  C  and  D  are  essentially  the 
same  as  in  the  Scheibler  apparatus  ;  A  being  the  decom- 
posing bottle  in  which  the  portion  of  the  sample  to 
be  operated  upon,  is  placed,  with  its  enclosed  tube  for 
the  decomposing  acid  or  other  solution,  with  the  further 
addition  however,  of  a  thermometer,  inserted  through 
the  rubber  stopper — a  most  important  feature  when  the 
decomposition  results  in  wide  variations  of  tempera- 
ture ;  C  the  bottle  containing  the  rubber  gas  balloon 
connected  with  A  ;  and  D  the  water  reservoir  with  com- 
pressing-bulb  E,  exactly  as  in  the  Scheibler  device. 
In  the  Scheibler  apparatus,  however,  the  gas  evolved  is 
directly  determined  by  the  displacement  of  water  in  a 
graduated  tube,  the  capacity  of  which  is,  and  must  be, 
quite  limited. 

^  Journal  of  tlie  American  Chemical  Society,  189.3,  page  614. 

35 


36  Volumetric  Apparatus. 

In  my  apparatus  I  have  replaced  this  graduated  tube 
by  the  bottle  B,  connected  by  the  tube  b  with  the 
space  around  the  rubber  bag  in  the  bottle  C,  and  by 
the  tube  r,  from  its  bottom,  through  the  stopcock,  with 
the  tube  L;  which  tube  L  connects,  through  another 
stopcock  at  its  opposite  end,  with  the  reservoir  D,  by 
means  of  the  tube  d.  This  tube  L,  which  may  be  con- 
structed of  brass  if  more  convenient,  is  fixed  horizon- 
tally upon  the  standards,  as  shown  in  the  cut,  and  has 
affixed  along  its  upper  portion,  a  series  of  stopcocks, 
one  of  which  connects  with  the  tube  F,  and  each  of  the 
others  individually,  with  the  pipettes  G,  H,  I  and  J, 
and  the  burette  K.  These  pipettes  may  be  respectively 
(using  a  fifty  cc.  burette  for  K)  50,  100,  200  and  200 
cc.  capacity,  graduated  as  to  contents,  between  marks 
on  the  stem  and  delivery  tube,  in  each  case.  The  tube 
F  serves  as  an  equalizer  of  pressure,  as  hereinafter 
described.  N  shows  a  common  tube  thermometer 
attached  to  the  standard  for  convenient  reference. 

Before  using  the  apparatus,  the  reservoir  D  is 
supplied  with  water,  and  by  means  of  the  compressing- 
bulb  E,  the  burette  and  pipettes  are  filled  to  their 
zero  marks,  and  their  respective  stopcocks  closed,  the 
stopcocks  connecting  c  and  F  being  closed  meanwhile. 
The  stopcock  connecting  c  is  now  opened,  and  the 
bottle  B  filled  a  little  above  a  zero  mark  upon  the  tube 
b^  which  for  a  portion  of  the  way  is  of  glass ;  this  glass 
tube  being  so  inserted  in  the  rubber  stopper  that  the 
bottle  may  be  entirely  filled  with  water  without  air 
space.  During  the  filling  of  B,  the  stopcock  M 
should   be    opened,    connecting   as    it  does  with  the  air 


Volumetric  Apparatus.  37 

space  surrounding  the  gas  bag  within  the  bottle  C, 
while  the  generating  bottle  A  should  be  disconnected 
and  the  gas  bag  collapsed.  When  B  is  filled,  the  stop- 
cock connecting  it  with  L  is  closed,  and  that  at  F 
opened,  and  this  tube  filled  in  like  manner  to  a  point 
higher  than  the  zero  mark  of  B,  when  the  stopcock 
connecting  d  is  closed,  and  that  at  c  opened  again. 
The  generating  bottle  A  with  its  charge  of  sample  and 
acid  in  the  tube,  is  now  connected,  and  through  the 
stopcock  connecting  d  the  level  of  the  water  in  B 
adjusted  to  the  zero  mark,  that  in  F  subsiding  with  it.^ 
When  the  adjustment  is  thus  effected,  the  stopcocks 
connecting  F,  and  that  at  M  are  closed,  while  that 
connecting  with  the  reservoir  through  </,  is  opened,  and 
thus  free  course  given  for  the  water  between  B  and  D. 
The  bottle  B  being  elevated  upon  the  shelf  O,  there  is  of 
course  a  reduction  of  pressure  within  the  apparatus, 
caused  by  subsidence  of  the  water  level ;  which  after  a 
few  moments  should  cease,  showing  that  the  apparatus 
is  tight  in  every  joint.  If,  however,  this  is  not  the  case, 
and  the  level  continues  to  subside,  there  is  a  leak,  which 
must  be  stopped  and  a  readjustment  of  pressure 
effected  before  the  operation  is  continued. 

When  all  is  in  readiness,  the  decomposition  of  the 
carbonate  is  effected  in  A  by  bringing  the  acid  and 
carbonate  together  in  the  usual  way,  the  temperature 
having  been  noted  at  the  outset.  The  evolution  of  the 
gas,  distending  the  rubber  gas  bag,  expels  a  portion  of 
the  air  from  C,  which  forces  the  water  from  B  into  the 

2  Experience  in  operating  this  apparatus  has  shown  that  it  is 
desirable  to  attach  a  U-tube  manometer  to  a  branch  placed  in 
tube  a,  near  its  connection  with  the  rubber  bag  in  C,  for  the  more 
accurate  adjustment  of  the  gas  to  atmospheric  pressure. 


38  Volumetric  Apparatus. 

reservoir  D,  in  volume  equivalent  to  the  gas  evolved  at" 
the  pressure  and  temperature  prevailing,  as  is  readily 
understood.  When  complete  decomposition  is  effected, 
and  the  temperature  in  A  returns  to  the  temperature  of 
the  room,  by  means  of  the  bulb  E,  pressure  is  exerted 
upon  the  reservoir  D,  and  the  stopcock  connecting  F 
being  opened,  the  levels  in  B  and  F  are  brought  together 
through  the  stopcock  connecting  d. 

When  this  is  accomplished,  the  stopcock  at  F  and  d 
are  closed.  It  is  seen  that  the  displacement  of  the 
water  in  B,  obtained  in  this  manner  is  exactly  that  of 
the  volume  of  the  gas  evolved  from  the  carbonate  at 
the  existing  temperature  and  atmospheric  pressure. 
With  all  stopcocks  closed,  excepting  that  connecting 
c,  and  that  at  M  which  should  now  be  opened,  the 
bottle  B  is  removed  from  its  shelf  to  the  table  upon 
which  the  apparatus  stands,  and  the  amount  of  the 
displacement  measured  by  running  in  the  contents  of 
such  of  the  pipettes,  and  portion  of  the  contents  of  the 
burette,  as  may  be  required  to  restore  the  water  level 
in  B  to  the  starting  point,  the  amount  of  water  thus 
employed  of  course  being  that  measure. 

From  the  volume  of  gas  obtained,  the  percentage  by 
weight  of  the  sample  taken  is  calculated  in  the  usual 
way,  either  by  the  formula  for  correction  of  volume 
for  temperature  and  pressure,  adding  of  course  to  the 
volume  thus  obtained  a  correction  for  carbon  dioxide 
dissolved  in  the  decomposing  liquid,  or  through  the  use 
of  the  tables  given  originally  by  Dietrich,  (Ztschr. 
anal.  Chem.,  4,  141).  It  is  to  be  noted,  however,  that 
these  tables  are  not  strictly  correct,   the  weight  of  the 


Volumetric  Apparatus.  39 

cubic  centimeter  of  carbon  dioxide  at  O*^  C.  760  mgms. 
being  considerably  at  variance  with  that  at  present  given 
by  the  best  authorities ;  and  some  sHght  errors,  in  the 
calculation  apparently,  are  also  to  be  observed.  In 
ordinary  work,  however,  these  are  not  important.  But 
in  the  use  of  the  table  given  for  solubility  of  the  gas  in 
the  decomposing  acid,  one  must  exercise  no  little 
caution.  In  fact  for  this  correction,  it  is  better  to 
establish  for  one's  self  just  what  it  should  be  for  each 
material  operated  upon,  by  check  gravimetric  deter- 
minations ;  for  while  within  limits,  this  may  be  taken  as 
a  constant  factor,  yet  it  is  more  or  less  affected  by  the 
character  of  the  salts  present.  And  further,  this  table 
was  not  carried  far  enough  to  cover  the  large  volumes 
of  gas  evolved  from  the  charges  that  my  apparatus 
enables  one  to  employ. 

With  this  apparatus  it  is  possible  to  make  a  deter- 
mination of  carbon  dioxide  in  from  ten  to  fifteen 
minutes,  and  that  with  extreme  accuracy.  Indeed  with 
the  large  charges  one  may  employ,  and  with  careful 
weighings,  repeated  results  obtained  from  the  same 
sample  will  never  vary  more  than  one-tenth  per  cent, 
and  scarcely  more  in  most  instances  than  two  or  three 
one-hundredths  per  cent. 

For  some  operations,  more  particularly  where  the  carbon 
dioxide  evolved  by  cold  water  is  to  be  determined  in  a  baking 
powder,  I  have  devised  the  fittings  and  arrangement  of  the 
decomposing  bottle  A,  as  shown  in  the  accompanying  cut. 

A  third  hole  is  pierced  through  the  stopper  of  A,  through  which  is 
introduced  the  stem  of  the  glass-stoppered  funnel  tube  P,  bearing 
the  stopcock  r,  and  having,  from  its  upper  portion,  the  air  tube  S, 
connecting  with  a  branch  inserted  in  the  tube  a.    It  is  readily  seen 


40  Volumetric  Apparatus. 

from  this,  that  the  weighed  charge  may  be  placed  in  A,  the 
stopper  inserted,  and,  with  the  stopcock  r  closed,  the  charge  of 
decomposing  liquid  placed  in  P,  and  the  stopper  of  P  also  inserted, 
when  connection  may  be  made  with  the  rest  of  the  apparatus  at 
a.  All  being  ready,  by  opening  the  stopcock  r,  the  Hquid  flows 
readily  into  A,  the  necessary  air  displacement  taking  place 
through  S,  the  rest  of  the  operation  being  conducted  as  above 
described. 


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Rumford  Chemical  Works, 

Providence,  R.  I.,  U.  S.  A. 
M.  L.  HORSFORD,  Pres't.         N.  D.  Arnold,  Treas. 


This  corporation  was  organized  in  1859,  for  the 
purpose  of  manufacturing  the  phosphatic  cuHnary 
preparations  invented  by  Professor  E.  N.  Horsford,  one 
of  the  founders  of  the  company,  then  Professor  of 
Chemistry  in  Harvard  University,  and  the  Rumford 
Professor  from  1847  to  1863.  The  manufacture  of 
other  special  chemicals  was  also  contemplated. 

In  recognition  of  the  Rumford  Professorship  and 
in  honor  of  its  founder.  Count  Rumford,  the  Works 
and  the  village  where  the  principal  manufacturing  plant 
is  located,  were  named. 

Productions. 
Phosphatic  Acid  Powder. — The  acid  constituent 
of  our  leavening  preparations,  Rumford  Yeast  Powder, 
Horsford's  Bread  Preparation  and  Rumford  Baking 
Powder ;  also  used  for  culinary  purposes,  by  families, 
bakers  and  manufacturers  of  self-raising  flours.  A  dry, 
white,  fine  powder,  having  for  its  active  principle  phos- 
phoric acid,  possessing  a  bicarbonate  of  soda  neutralizing 
strength  equivalent  to  that  of  cream  of  tartar.  Prepared 
in  several  varieties  adapted  to  the  various  uses. 

Rumford  Yeast  Powder. — A  mixture  of  our  phos- 
phatic acid   powder,   bicarbonate  of  soda   and  starch. 
43 


44  Productions. 

Packed  in  sealed  glass  bottles  of  various  sizes.  The 
original  name  and  form  of  packing  used  for  the  phos- 
phate baking  powder. 

Horsford*s  Bread  Preparation. — A  baking  powder, 
composed  of  our  phosphatic  acid  powder  and  bicar- 
bonate of  soda  put  up  in  separate  papers ;  these  being 
wrapped  together  to  form  one  package.  An  early 
name  and  form  of  package  used  for  the  phosphate 
baking  powder. 

RUMFORD  BAKING  POWDER. 

A  mixture  of  our  phosphatic  acid  powder^  bicarbonate 
of  soda  and  starchy  identical  in  leaveni^ig  quality  with 
Rtcmford  Yeast  Powder  and  Horsford' s  Bread  Prepara- 
tioHy  but  packed  ht  tin  cans  of  the  usual  sizes.  Prepared 
by  the  latest  improved  process  to  retain  its  strength 
indefinitely. 

Horsford's  Acid  Phosphate. — A  liquid  medicinal 
preparation  of  the  phosphates,  for  diseases  of  the 
nervous  and  digestive  systems. 

Horsford's  Dicalcic. — A  powdered  medicinal  calcium 
phosphate,  without  free  acid,  readily  soluble  in  the 
juices  of  the  stomach.  Serviceable  where  deficiency 
of  lime  is  indicated.  A  corrective  in  acidity  of  the 
stomach,  and  a  remedy  in  certain  forms  of  dyspepsia. 

Horsford's  Anti-Chlorine. — A  dry,  white,  fine  powder 
for  neutralizing  chlorine  and  acid  in  paper  stock. 


^HIS  BOOK  ON  THE  ^^^^  °  ^  ^^  THE  FOURTH 
O  V  ERD  U  E.  == 


MMI  31  1^' 


APR  14=193: 
NOV  19  1935 


LD  21-50m-l,'3' 


Pressboard 

Pamphlet 

Binder 

Gaylord  Bros.,  Inc. 

Makers 
Stockton,  Calif. 

PAT.  JAN.  21.  1908 


"^r 


rx 

CD 

THE  UNIVERSITY  OF  CALIFORNIA  LIBRARY 


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